包装材料阻隔性能对黄酒风味的影响

中国市场上的黄酒普遍采用复合膜袋、玻璃瓶、陶瓷瓶、塑料桶及利乐枕等包装形式,不同包装材料的阻隔性能差异较大,对成品黄酒的风味产生不同的影响。为了检测不同包装材料中黄酒风味的变化情况,通过压差法,库仑计检测法,杯式法,红外传感器法,浊度检测法,固相微萃取法和酒精度、总酸、总糖、氨基酸态氮检测法对包装材料的氧气透过率和水蒸气透过率,黄酒的浊度,醇、酯、醛的含量和理化指标进行检测。经试验发现,复合膜的阻隔性能最差,氧气透过率和水蒸气透过率均很高分别为1 448 cm3/(m2·24 h·0.1 MPa)和2.09 g/(m2·24 h)。成品酒贮存3~6个月内,已经出现明显的风味损失,贮存1年后,出现大量沉淀。因此阻隔性能较差的包装材料不适合作为黄酒的包装使用。塑料桶的阻隔性能居中,氧气透过率虽较高,但水蒸气透过率较低。HDPE塑料桶会加速酒体的氧化,使得浊度和多种挥发性物质含量上升,不利于保持风味的稳定性,货架期应设置在1年以内。利乐包、玻璃瓶和陶瓷瓶的阻隔性能较好,氧气透过率和水蒸气透过率均较低。贮存1年后,沉淀较少,且黄酒风味含量保持相对稳定。对贮存1~17年的玻璃瓶包装产品进行了理化指标和风味分析,产品品质良好,仍然适合饮用。黄酒中大部分风味物质含量保持稳定,但在微溶氧的影响下,醛类化合物的含量上升,说明黄酒贮存在玻璃容器中,也发生陈酿的变化。     

Modelling the respiration rate of minimally processed broccoli (Brassica rapa var. sylvestris) for modified atmosphere package design

In this work, the effect of temperature, oxygen and carbon dioxide on the respiration rate of minimally processed broccoli was studied to develop suitable modified atmosphere packaging. Respiration rate was measured at 3, 5, 7, 10, 15 and 20 °C under different gas compositions of O₂ and CO₂ (1%, 5%, 10%, 15% and 21% of O₂ with the balance N₂, a mixture of 10% and 20% of carbon dioxide with the balance air and a mixture at 3% of O₂ and 15% of CO₂ with the balance N₂). As expected, temperature was the most influential factor on respiration rate, for all atmospheres tested: increasing the temperature from 3 to 20 °C resulted, for air‐stored samples, in a 84% change in oxygen respiration rate, whereas at constant temperature, the respiration rate decreased by 35% with lowering the O₂ concentration from 21% to 1% and by 44% with increasing the CO₂ concentration from 0% to 20%. The Michaelis and Menten competitive model with maximum respiration rate varying against temperature with an Arrhenius equation accurately described the influence of gas composition and temperature on the respiration rate of minimally processed broccoli, and it was used to design a suitable package.     

薄膜包装中果蔬呼吸强度的两种测定方法之比较研究

本文以香蕉果实为例,在不同的温度条件下(10、15、20、25、30℃)用已测得透气系数的低密度聚乙烯薄膜(LDPE)来进行香蕉的薄膜包装(MAP)贮藏。用数理法和密闭法分别测定MAP条件下香蕉在贮藏期间内的呼吸强度,并对两种测定方法的测定结果进行了比较。研究结果表明：密闭法测得的果蔬呼吸强度比数理法测定的结果偏低。两种方法所得结果的差异,可以从各自不同的测定原理得到解释。     

高氧气调包装对鲜切莴苣呼吸和酶活性的影响

以空气包装的鲜切莴苣为对照,研究了60%O2﹢20%CO2﹢20%N2和100%O2高氧气调包装的鲜切莴苣在4℃贮藏14d期间呼吸强度和酶活性的变化。结果表明:高氧气调包装对鲜切莴苣呼吸和酶活性影响显著,60%O2﹢20%CO2﹢20%N2和100%O2高氧气调包装显著抑制鲜切莴苣的呼吸,且100%O2气调包装的抑制效果优于60%O2﹢20%CO2﹢20%N2气调包装;60%O2﹢20%CO2﹢20%N2和100%O2高氧气调包装促进SOD酶活性的上升、抑制O2-.生成量的增加和PPO、PAL酶活性的上升。     

Mathematical modelling of O2 consumption and CO2 production rates of whole mushrooms accounting for the effect of temperature and gas composition

Investigation of respiration rate of fresh produce, under different gas composition and temperatures, and respective mathematical modelling is central for the modified atmosphere packaging design. This work investigates the effect of temperature (4, 8, 12, 16, 20 °C) and gas composition (O₂ between 3 to 21% and CO₂ between 0 to 15%) on respiration rate of whole mushrooms. Oxygen and carbon dioxide respiration rates increased significantly (3–4 fold) as the temperature elevated from 4 to 20 °C and were in the range of 13.23 ± 3.12 to 102.41 ± 2.132 mL kg⁻¹ h⁻¹) and 14.33 ± 1.56 to 97.02 ± 2.51 mL kg⁻¹ h⁻¹) respectively. Low O₂ and high CO₂ levels reduced O₂ consumption and CO₂ production rates of whole mushrooms on average by a circa 47–60% at all temperatures as compared to the respiration rate at ambient air. Mathematical models were developed for RO₂ and RCO₂, by combining the Arrhenius and Michaelis–Menten uncompetitive equations. These models predicted well, O₂ consumption and CO₂ production rates of whole mushrooms as a function of both temperature and gas composition.     

Influence of oxygen concentration and temperature on respiratory characteristics of fresh-cut green onion

The characteristics of the respiration rates in precut green onion, as influenced by oxygen levels and temperature, were examined to provide design factors for modified atmosphere packaging (MAP). Fresh-cut green onions ( Allium fistulosum L.) were prepared and sealed, with and without a CO₂ absorbent, in gas-tight glass containers that had initially been purged with air or a gas mixture (O₂ 9%/N₂ balance). The containers were stored at different temperatures (0, 10, 20 °C). At 10 °C, the maximum O₂ uptake rate (V_m) and the O₂ concentration at half-maximum (K_m) uptake rate were 30.95 mL kg⁻¹ h⁻¹ and 1.63%, respectively. Regardless of temperature, the lower O₂ limit was estimated to be about 1.0% O₂ on the basis of respiratory quotient (RQ) increase. Respiration of cut green onion was dependent on O₂ concentration as well as temperature, as shown by applying the Michaelis–Menten type model and the Arrhenius equation. However, the presence of CO₂ had little effect on O₂ uptake of cut green onion at relatively high O₂ concentrations (≤20%).     

锦绣黄桃主动气调包装研究

探讨了主动气调包装用于果蔬采后品质保持的优越性。建立了锦绣黄桃主动气调包装的数学模型,测定了不同冷藏温度下黄桃的呼吸速率,给出了Michaelis-Menten型呼吸速率方程。进行了0℃、5℃和10℃下黄桃AMAP贮藏实验,袋内气体分析采用气相色谱仪一次进样测定的新方法。实验结果表明,贮藏温度和包装材料特性是影响黄桃贮藏品质的主要因素,采用实验推荐的处理组合可取得满意的保鲜效果。     

Modelling the respiration rate of fresh-cut Annurca apples to develop modified atmosphere packaging

In this work, the effect of temperature, oxygen, red coloration process and post-harvest storage time on the respiration rate of fresh-cut Annurca apples was studied to properly develop modified atmosphere packaging. Our results showed that the red coloration process and the post-harvest storage time did not affect the respiration rate or the respiratory quotient of fresh-cut Annurca apples in the range of temperature studied (5–20 °C). A Michaelis–Menten-type equation, with the model constants described by means of an Arrhenius-type relationship, was used for predicting respiration rate on varying the temperature and O₂ concentration in the head space. The maximal respiration rate (mL kg h⁻¹) (RR_max) and the O₂% corresponding to     values estimated at the reference temperature (12.5 °C), i.e. the average of the experimental temperature ranges, were, respectively, 6.77 ± 0.1 mL kg⁻¹ h⁻¹ and 0.68 ± 0.07% v/v, and the activation energy of the aerobic respiration rate of fresh-cut Annurca apples was estimated at 51 ± 1 kJ mol⁻¹. The model works well to develop a modified atmosphere for fresh-cut Annurca apples.     

气调保鲜包装初始气体浓度配比对番木瓜品质的影响

采用厚度75.8μm的PP复合膜对番木瓜室温下气调保鲜包装的技术进行研究。结果表明:气调保鲜技术可以降低番木瓜失水率、减缓表面变黄速率、防止硬度下降、减少可溶性固形物含量、防止VC的大量损失。评定指标选用了硬度、色泽、失水率、VC含量、可溶性固形物、pH值、感官评定。结论得出:番木瓜气调保鲜包装的平衡气体浓度为O24.2%～4.9%,CO27.3%～7.9%;番木瓜气调保鲜包装内气体最佳初始浓度为3%O2、9%CO2、88%N2;测得室温下气调包装达到平衡时,番木瓜的呼吸强度为0.2～0.4ml/kg·hCO2。     

青豌豆呼吸速率的测定与模型表征

呼吸速率的测定与模型表征是实现果蔬气调包装的基础。采用封闭系统、渗透系统法测算青豌豆呼吸速率,应用Michaelis-Menten式方程、二次方程式进行呼吸速率模型参数表征。结果表明,封闭系统法测算值较渗透系统法低,模型结果与测定值比较吻合。     

温度对薄膜包装中气体浓度和香蕉呼吸强度的影响

在设定的10、15、20、25、30℃五个温度条件下,用已测得透气系数的低密度聚乙烯薄膜(LDPE)进行香蕉的薄膜包装贮藏试验。结果表明(1)温度越低,系统达到平衡状态所需要的时间越长,反之,所需时间越短;(2)O2和CO2浓度与温度之间的关系可以用曲线方程来描述;(3)香蕉的O2吸收速率Ro和CO2释放速率Rc的自然对数值和绝对温度的倒数值之间的关系可以通过阿伦纽斯方程(Arrhenius’equation)来描述;(4)温度对果蔬呼吸强度的影响大于温度对薄膜透气性的影响。     

不同气调包装对薄荷贮藏品质的影响及薄荷保鲜呼吸速率模型的建立

为了提高薄荷采后贮藏时间和预测薄荷采后的呼吸速率,通过失重率、相对电导率、色差、感官评分、维生素C含量、总叶绿素含量和菌落总数指标的测定,从包装材料为聚乙烯包装（PE）、邻苯基苯酚复合聚乙烯包装（OPP1.8/PE3.5、OPP1.8/PE4.5、OPP2.3/PE4.5）、高密度聚乙烯包装（HDPE）,O₂浓度为3%~7%,CO₂浓度为5%~15%中筛选薄荷的气调包装条件,并以O₂、CO₂和包装材料为因素开展响应面优化试验,优化薄荷采后保鲜的最优气体比例及包装材料,在此基础上研究薄荷挥发性化合物和表面真菌多样性。使用密闭空间系统法测量薄荷在最优包装材料内O₂和CO₂的比例。在此基础上,再采用渗透系统法得到模型方程,并对其进行数值模拟。运用Matlab软件对处于平衡点时的呼吸速率进行计算,利用二次多项式模型对结果进行回归分析。利用高通量测序对最优、最差和对照处理组的薄荷进行测序和分析,比较其优势菌群的占比变化。结果表明：最优气调比例及包装材料为3.5% O₂+9.4% CO₂和HDPE,该包装方式可将薄荷的保鲜期由7~9 d延长至10~12 d,可抑制薄荷贮藏期间芳樟醇等醇类物质的增加,减少D-香芹酮等酮类物质的挥发,延缓薄荷衰老,基于以上实验结果建立薄荷二次多项式呼吸速率模型,并能够更准确设计薄荷的气调包装条件,较好地抑制薄荷贮藏期间子囊菌门和霉菌门等腐败菌的生长。     

基于包装内顶空氧气浓度变化的奶粉货架期预测

目的：通过包装顶空氧气浓度变化确定全脂奶粉耗氧量,进而预测包装奶粉货架期。方法：利用相对耗氧率表征全脂奶粉氧化特性,分析多个氧化指标确定奶粉耗氧量阈值;综合包装材料氧气渗透性与奶粉氧化特性表征顶空氧气浓度变化,建立奶粉耗氧总量模型预测奶粉货架期;结合45℃下聚对苯二甲酸乙二脂/聚乙烯袋装全脂奶粉加速氧化实验进行模型验证。结果：全脂奶粉耗氧量阈值为0.041 47 mg/g,加速氧化贮藏期间包装顶空氧气体积分数实验数据和模型预测数据规律一致,实验货架期和理论预测货架期的相对偏差为6.06%。结论：可通过包装顶空氧气体积分数变化来预测全脂奶粉包装货架期。     

不同温湿度对奶粉包装膜水蒸气透过率的影响

主要研究了不同温度(25~38℃)和湿度(RH35%~90%)对奶粉包装膜的水蒸气透过率的影响。试验结果表明,该奶粉包装膜在一定相对湿度时,水蒸气透过率随温度的升高而升高;在一定温度时,水蒸气透过率随相对湿度的升高而升高;温度越高,相对湿度越大,该奶粉包装膜的水蒸气透过率越大。